Measurement of the 𝑡-channel single top quark cross section in proton-proton collisions at √𝑠 = 13 TeV

Abstract

The observation of the electroweak production of single-top-quarks is made using 255 pb⁻¹ of proton-proton collision data recorded at √𝑠 = 13 TeV with the ATLAS detector at the Large Hadron Collider. An event selection is used to identify single-top-quark candidates arising from t-channel production with the top quark decaying semi-leptonically. Events passing the selection are then used to measure the inclusive cross-section for the combined production of single-top-quarks and antiquarks, σ(𝑡𝘲 + 𝘵̅𝘲), and the ratio 𝘙_𝑡 between these two. They are measured to be σ(𝑡𝘲 + 𝘵̅𝘲) = 27.1^+4.4_−4.1(stat.)^+4.4_−3.7(syst.) pb and 𝘙_𝑡 = 2.73+1.43−0.82(stat.)+1.01−0.29(syst.). The individual single-top-quark (𝑡𝘲) and single-top-antiquark (𝘵̅𝘲) production cross-sections are measured to be σ(𝑡𝘲) = 19.8^+3.9</sub>−3.1</sub>(stat.)^+2.9</sub>−2.2</sub>(syst.) pb and σ(𝘵̅𝘲) = 7.3^+3.2_−2.1(stat.)<sup>+2.8_−1.5(syst.) pb. All measurements are in good agreement with the Standard Model predictions.